1. Field of the Invention
The present invention relates in general to mineral recovery wells, and in particular to a control system for actuating hydraulic devices.
2. Brief Description of Related Art
Downhole devices are often used in a wellbore. Typical downhole devices can include, for example, flow control valves, hydraulic packers, and any variety of hydraulically actuated downhole tools. These downhole devices are typically controlled by hydraulic pressure, particularly because electronic controls cart be unreliable in high pressure, high temperature conditions that often exist in a wellbore. The hydraulic lines which control these downhole devices must pass through various well components such as, for example, tubing hangers. It can be difficult to pass a sufficient number of hydraulic lines through a tubing hanger, to control each and every downhole device.
Some systems exist which use Boolean logic to control multiple downhole devices from a relatively small number of lines. These systems can use, for example, multiple pulses of pressure to actuate a particular downhole device. Unfortunately, such Boolean systems can be unreliable.